Fair Value Fair Value (Schedule of Availability of Significant Unobservable Inputs by Balance Sheet Classification) (Details) (Fair Value, Inputs, Level 3 [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Assets, Fair Value Disclosure	$ 6,518
Liabilities, Fair Value Disclosure	109
Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Assets, Fair Value Disclosure	398	[1]
Liabilities, Fair Value Disclosure	109	[1]
Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Assets, Fair Value Disclosure	6,120	[2]
Liabilities, Fair Value Disclosure	0	[2]
Mortgage Backed Securities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	906
Mortgage Backed Securities [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	906	[2]
Asset-backed Securities, Student Loans [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	478
Asset-backed Securities, Student Loans [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	12	[1]
Asset-backed Securities, Student Loans [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	466	[2]
Asset-backed Securities, Credit Cards [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	238
Asset-backed Securities, Credit Cards [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	138	[1]
Asset-backed Securities, Credit Cards [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	100	[2]
Asset-backed Securities, Other [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3,460
Asset-backed Securities, Other [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	101	[1]
Asset-backed Securities, Other [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3,359	[2]
Non-US Debt Securities, Mortgage-Backed Securities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	285
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[1]
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	285	[2]
Non-US Debt Securities, Asset-Backed Securities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	677
Non-US Debt Securities, Asset-Backed Securities [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[1]
Non-US Debt Securities, Asset-Backed Securities [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	677	[2]
Non-US Debt Securities, Other [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	194
Non-US Debt Securities, Other [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[1]
Non-US Debt Securities, Other [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	194	[2]
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	48
US States and Political Subdivisions Debt Securities [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	48	[1]
US States and Political Subdivisions Debt Securities [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[2]
Collateralized Mortgage Obligations [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	124
Collateralized Mortgage Obligations [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[1]
Collateralized Mortgage Obligations [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	124	[2]
Other U.S. Debt Securities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	9
Other U.S. Debt Securities [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0	[1]
Other U.S. Debt Securities [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Available-for-sale Securities, Fair Value Disclosure	9	[2]
Derivative Financial Instruments, Liabilities [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	100
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	9
Derivative Financial Instruments, Liabilities [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	100	[1]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	9	[1]
Derivative Financial Instruments, Assets [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	99
Derivative Financial Instruments, Assets [Member] | Significant Unobservable Inputs Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	99	[1]
Derivative Financial Instruments, Assets [Member] | Significant Unobservable Inputs Not Readily Available [Member]
Fair Value, Measurements, Availability of Significant Unobservable Inputs [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	$ 0	[2]

[1] Information with respect to these model-priced financial assets and liabilities is provided in the preceding table.

[2] Fair value for these financial assets is measured using non-binding broker or dealer quotes.